Mercury – Mercury starts the month very low in the ENE dawn sky but is quickly lost over the next few days. It doesn’t take long to reappear and by the last week of June it can be seen low in the WNW 45 minutes or so after sunset. During the last few nights of the month, Mercury makes a nice trio with the bright stars of Gemini, Castor and Pollux. All three can be seen in a 11° long straight line on June 30.

Saturn – Saturn is now well past opposition at magnitude +0.8. It starts the night near its highest point on the meridian to the south. The planet is observable for the rest of the evening. Saturn is a slow moving planet and takes 29 years to circle the Sun as well as 29 years to do one circuit around the ecliptic constellations. As has been the case all year long, Saturn is still located in Virgo about 13-14° from 1st magnitude Spica. The planet is making a nice “double star” with 3rd magnitude Gamma Virginis. The two are within 0.25° of each other on June 9.

Jun 10 - Saturn and Moon 8° apart

Morning Planets

Jupiter – Jupiter rises 2 to 3 hours before sunrise and is well up in the eastern sky as dawn begins. Shining at magnitude -2.2 the King of the Planets will be the brightest ‘star’ in the sky over the next few months.

Jun 26 - Moon 5° from Jupiter

Mars – Located 16° to the lower left of Jupiter at the start of the month, the gap increases all month long. Mars is a fast moving planet meaning it does a good job of keeping up with the Sun and as a result will only slowly rise higher in the sky from month to month. Though a relatively faint magnitude +1.4 (for a planet), it will get much brighter as it moves towards opposition in March 2012.

Jun 28 - Moon 2° from Mars

Venus – Venus will be a very difficult sight low in the ENE during dawn. Towards the end of the year, it will be a much easier sight as an evening object.

Meteors

Meteor activity is still near a seasonal minimum in June. The year is usually split in 2 with January through June having low rates with few major showers while July through December have high rates with many major showers.

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During June mornings, 10-12 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

None this month

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors. Starting this month, info on most of the minor showers will be provided on a weekly basis by Robert Lunsford’s Meteor Activity Outlook.

Comets

Naked Eye Comets (V < 6.0)

None this month…

Binocular Comets (V = 6.0 – 8.0)

None this month…

Small Telescope Comets (V = 8.0 – 10.0)

C/2009 P1 (Garradd)

Last month I mentioned how there always seems to be a bright Comet McNaught or Comet Garradd in the sky. Well last month’s Comet McNaught (C/2011 C1) has now faded below 10th magnitude but it has been replaced by a Comet Garradd (C/2009 P1). First seen way back on August 13, 2009 by Gordon Garradd, this is yet another discovery by the Siding Spring Survey, a NASA-funded survey observing from Australia. At the time of discovery it was located at a distance 8.7 AU from the Sun, nearly the distance of Saturn. Perihelion will occur 2 days before Christmas 2011 at 1.55 AU from the Sun. Though the comet does get very close to the Sun, it is an intrinsically bright comet and may be a borderline naked eye object for observers at very dark sites (6th magnitude).

The comet starts the month at a distance of 3.04 AU from the Sun and 2.96 AU from Earth. At mid-month it is 2.91 AU from the Sun and 2.58 AU from Earth and by month’s end it will be 2.76 and 2.19 AU from the Sun and Earth, respectively. Visual observers are placing the comet at magnitude 10.0 to 10.5 at the end of May. It should brighten to magnitude 9.0 to 9.5 by the end of the month as it slowly moves north near the Pisces/Aquarius border.

Asteroids

Binocular and Small Telescope Asteroids (V < 8.0)

(4) Vesta

Vesta is the brightest asteroid in the Main Belt. This is due to its high albedo (or reflectivity) which causes it to reflect ~42% of the light that strikes it. Vesta is also peculiar in that it appears to have evidence of volcanism on its surface. Similar to the Moon, Vesta may be covered with large expanses of frozen lava flows. It is classified as a V-type asteroid and is the only large asteroid with this classification. Many of the smaller V-type asteroids are chips of Vesta blasted off it by past asteroid and comet impacts. Vesta has dimensions of 347x336x275 miles or 578×560×458 km.

The maps below were created from images taken with the Hubble Space Telescope. The geography is dominated by a large impact crater located near the south pole (the blue ‘donut’ in the elevation map). Perhaps this crater is the result of the impact that blasted off the smaller V-type asteroids. We’ll know more this summer when NASA’s Dawn spacecraft enters orbit around Vesta for a full year. Currently the encounter is scheduled for July 2011 to July 2012 though images showing more details than those from HST may be released this month.

Images and models of the shape of asteroid (4) Vesta. In the upper left is a real HST image, to the upper right is a model of Vesta’s shape, and on the bottom is an elevation map . Credit: NASA/STScI.

Vesta spends the month around magnitude 6.9 to 6.3 as it begins its retrograde loop in western Capricornus. Opposition is on August 4 at magnitude 5.6.

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